As already stated Pan Am B707's with freight doors were fitted with a system called 'STANS' from as early as 1965 (believe it was a customer option on all production B707's with freight door fitted)which used the moment/transducer type weighing system to give a weight on an indicator/readout in the cockpit - operating a B707-321C in late 90's it was still fitted and appeared remarkably accurate
I have never seen this system or anything like it in any other Western aircraft